[en] Ferromagnetic superconductors are superconducting at low temperatures, but below a certain temperature they become ferromagnetic and the superconductivity breaks down. In an intermediate state coexistence of superconductivity and ferromagnetism is observed. A generalised Ginzburg-Landau mean-field model is used to describe the superconductivity, the magnetisation and their mutual competition. Coexistence of superconductivity and magnetism is only possible through spatial varying structures which can be complicated because of the non-local character of the electromagnetic interaction. An easy-axis magnetic anisotropy is considered in the paper. The structures known so far are discussed and a new alternating vortex lattice structure is developed which combines both Bloch walls in the magnetisation and vortex lines in the superconductivity. This structure can have the lowest free energy of all structures over a certain temperature interval. (author)